Ligation, as it relates to the present specification, is a medical procedure used to remove unwanted anatomical structures from the human body. Elastic or rubber band ligation involves the placement of a constricting band about the unwanted anatomical structures, such as a blood vessel or the base or pedicle of a lesion, to occlude distal blood supply. After the loss of blood supply, the lesion slowly dies, sloughs off, and is passed from the body. Elastic ligation is used in the treatment of conditions such as internal hemorrhoids and mucous colitis.
Typical ligation procedures are performed using a ligating device affixed to the distal end of an endoscope. The ligating device includes one or more elastic bands positioned on its distal end. During the procedure, an elastic band that has been stretched outwardly beyond its relaxed, loop configuration is placed around the proximal portion of an outdrawn target tissue. The band is released and thereafter naturally constricts back to its non-stretched configuration, thereby putting pressure on the target tissue and cutting off blood supply to the distal portions.
U.S. Pat. No. 6,007,551, assigned to Dabegran Technologies, Inc. and Cook Medical Technologies LLC, discloses “An endoscopic ligation apparatus for use with a flexible endoscope having a plurality of channels therethrough including a working channel opening at an auxiliary port, said apparatus comprising: a hollow barrel defining an outer surface and a hollow interior therethrough, and including a distal end and a proximal end; means for mounting said proximal end of said barrel to the insertion end of the flexible endoscope; at least one elastic ligating band removably mounted on said outer surface of said barrel; and a trip wire configured to extend through the working channel of the endoscope and including; a proximal end and a distal end, and a length between said ends sufficient for said distal end to extend beyond the insertion end of the endoscope while the proximal end extends from the auxiliary port; a plurality of strands at said distal end, each of said strands extending through said hollow interior of said barrel beyond said distal end of said barrel and overlaying said outer surface of said barrel underneath said at least one ligating band; and each of said plurality of strands including a least one bead attached thereto and situated adjacent said at least one ligating band between said band and said proximal end of said barrel, whereby tension applied to said proximal end of said trip wire pulls each of said plurality of strands toward said distal end of said barrel such that said bead on each of said strands engage said at least one ligating band to dislodge said band from said barrel, wherein said trip wire includes a bead attached thereto adjacent said proximal end.”
U.S. Pat. No. 6,676,672, assigned to SciMed Life Systems, Inc., discloses “A ligating band dispenser, comprising: a support surface having a channel extending substantially therethrough, the support surface having an outer surface; and a plurality of ligating bands supported on the outer face of the support surface; a pull line extending through the channel and generally circumferentially along the outer surface of the support surface, the pull line having a plurality of knots formed thereon, each of the plurality of knots having a diameter greater than a diameter of the pull line, each of the plurality of knots being retained proximally of a corresponding one of the plurality of ligating bands, wherein the pull line loops around a selected one of the plurality of ligating bands.”
While current ligation devices have proven to be effective in removing unwanted tissues, they are not without their drawbacks. For example, ligation devices that employ more than one pull line or multiple strands are more difficult to manufacture and use. The presence of multiple wires can also obscure vision when using the device. In addition, current multi-band ligation devices often encounter problems with deploying all of the bands. Specifically, the bands loaded more proximally on the device, and therefore slated to be deployed last, often misfire. When the band is stretched to the diameter of the device, the geometry of the band becomes more compliant, allowing the band to jump over the bead or knot as the line is pulled and resulting in the misfire. Misfired bands remain on the device resulting in unsuccessful treatment of the lesion.
Therefore, what is needed is a multi-band ligation device that has an improved, more reliable deployment mechanism, particularly for the proximal bands.